- Phase I (patients with glioma or meningioma) Patients in cohorts 1 and 2 receive oral imatinib mesylate (STI571) once daily on days 1-28. Patients in cohorts 3-5 receive oral STI571 twice daily on days 1 and 3-28 of the first course and on days 1-28 of subsequent courses. Courses repeat every 4 weeks in the absence of disease progression or unacceptable toxicity.